VARIATION IN THE INFLUENCE OF SELECTED SOCIODEMOGRAPHIC RISK-FACTORS FOR MENTAL-RETARDATION

Objectives, This study explored the utility of subdividing mental reta rdation into groups based on the presence of other neurological condit ions. Methods. Data were abstracted from birth certificates as part of a case-control study of mental retardation among 10-year-old children . The study sample included 458 case children and 563 control children selected from public schools. Case children were subdivided on the ba sis,of intelligence. quotient: (IQ) score and the presence of other ne urological conditions. Results. Other neurological conditions, were mo re common with severe mental retardation than with mild mental retarda tion. Regardless of IQ level or the presence of other neurological con ditions, boys were more likely than girls to have mental retardation. Older mothers were more likely than younger mothers to have a child wi th mental retardation accompanied by another neurological condition, H igh birth order, Black race,and low maternal education were associated with a higher prevalence of isolated mental retardation. Conclusions. These findings suggest,that sociodemographic risk factors for mental retardation vary according to the presence of other neurological condi tions and that subdivisions based on medical or physical criteria may be useful in epidemiologic studies of mental retardation.